A tunable optical device based on liquid crystal technology has many advantages over existing alternatives. These advantages and the tunable liquid crystal lens (TLCL) technology are discussed in detail in PCT publication WO2007/098602 dated Sep. 7, 2007. The devices may be compact, have no moving parts and are tunable to change optical properties, such as focus, magnification, steering angle, etc. In these devices, transparent electrodes are included that require electrical connection. For many applications, low cost is an important feature.
The ability of liquid crystal to modulate the propagation of light depends on the difference in optical properties in different directions with respect to the liquid crystal molecules. In PCT WO2007/098602 it is shown in FIG. 11 that a liquid crystal layer may act to focus light in a single polarization plane, and that two liquid crystal layers can be arranged to act on different polarization planes. This leads to tunable liquid crystal devices that have a plurality of liquid crystal layers.